Substrate processing apparatus and semiconductor device producing method

ABSTRACT

Disclosed is a substrate processing apparatus which comprises reaction tubes ( 3,4 ) for processing multiple substrates ( 27 ), a heater ( 5 ) for heating the substrates, and gas introducing nozzles ( 6,7,8,9,10 ) for supplying a gas into the reaction tubes. Each of the gas introducing nozzles ( 6,7,8,9 ) is structured so that at least the channel cross section of a portion facing the heater ( 5 ) is larger than those of the other portions.

TECHNICAL FIELD

The present invention relates to a substrate processing apparatus, andmore particularly, to a substrate processing apparatus such as avertical CVD (Chemical Vapor Deposition) apparatus which produces asemiconductor device such as an IC on a substrate such as a siliconwafer.

BACKGROUND ART

As the substrate processing apparatus, there is a batch type substrateprocessing apparatus which processes a necessary number of substrates ata time, e.g., a vertical CVD apparatus which has a vertical reactionfurnace and which processes a necessary number of substrates at a time.

For producing semiconductor devices, a batch type vertical hot walldecompression CVD apparatus is widely used for forming a CVD film such apolycrystalline silicon film, a silicon nitride film and the like on asubstrate (wafer).

A general batch type vertical hot wall decompression CVD apparatusincludes a reaction tube comprising an inner tube and an outer tubewhich is concentric with the inner tube, a heater which is disposed suchas to surround the outer tube and which heats the inside of the reactiontube, a gas introducing nozzle through which reaction gas is introducedinto the inner tube, and a vertical furnace comprising an exhaust portor the like through which the reaction tube is evacuated. A necessarynumber of multi-stacked wafers are held in their horizontal postures andin this state, the wafers are brought into the inner tube from below.Reaction gas is introduced into the inner tube through the gasintroduction nozzle, and the inside of the reaction tube is heated bythe heater, thereby forming CVD films on the wafers.

As such a conventional substrate processing apparatus, there is avertical CVD apparatus as described in Japanese Patent ApplicationLaid-open No. 2000-68214 for example.

This vertical CVD apparatus includes a plurality of reaction gas supplynozzles as the gas introducing nozzle. A quartz tube having ¼ inchdiameter (outer diameter) is used as the reaction gas supply nozzle.Each reaction gas supply nozzle comprises a horizontal portion which isinserted below the inner tube from the horizontal direction, and avertical portion which extends upward along an inner surface of theinner tube, and the reaction gas supply nozzle is formed into L-shape.The vertical portion is provided in a gap between the inner tube, a boatand a wafer held by the boat. An upper end of the vertical portion isopened. Lengths of vertical portions of the respective reaction gassupply nozzles are different from one another in stages so that reactiongas can be dispersed and supplied into the inner tube.

When a CVD film is to be formed on a wafer, a reaction product is formednot only on the wafer surface, but is also adhered to and deposited onan inner surface of the inner tube 3 or an interior of the reaction gassupply nozzle 106 as shown in FIG. 13. Especially a portion of thereaction gas supply nozzle 106 that is opposed to the heater 5 is heatedby the heater 5 and thus, there is a high tendency that the reactionproduct 47 is adhered to and deposited on this portion of the reactiongas supply nozzle 106. Further, since the pressure in the reaction gassupply nozzle 106 is higher than the pressure outside of the nozzle 106,a reaction product 47 adhered to an inner wall of the nozzle 106 isthree to four times thicker than a reaction product adhered to an outerwall of the nozzle 106. For this reason, when a flat polycrystallinesilicon film (this will be described later) having about 5,000 to 10,000Å thickness is to be formed using a quartz tube having ¼ inch diameter(outer diameter) as the nozzle 106, the nozzle 106 is clogged duringprocessing of three to four batches. In this case, cleaning of thenozzle can not be carried out, and the only way is to replace the nozzle106 with a clean one every three to four times batch processing.Therefore, maintenance operation such as cleaning of the reaction gassupply nozzle must frequently be carried out under the necessity, andthis deteriorates the rate of operation and throughput of the substrateprocessing apparatus.

In view of such circumstances, it is a main object of the presentinvention to prevent a gas introducing nozzle from being clogged sooneven if a thick film such as a thick polycrystalline silicon film isformed, to elongate a maintenance cycle, to reduce downtime of theapparatus, to lighten the maintenance operation, and to enhance thethroughput.

DISCLOSURE OF THE INVENTION

According to an aspect of the present invention, there is provided asubstrate processing apparatus characterized by comprising:

a reaction container which processes a plurality of substrates;

a heater which heats said plurality of substrates; and

at least one nozzle through which reaction gas is supplied into saidreaction container, wherein said nozzle is attached to said reactioncontainer with said nozzle penetrating a wall of said reactioncontainer, and a flow-path cross-sectional area of a portion of saidnozzle that is opposed to at least said heater is greater than aflow-path cross-sectional area of the nozzle-attaching portion.

According to another aspect of the present invention, there is provideda producing method of a semiconductor device characterized bycomprising:

a step for transferring a substrate or a substrates into a reactioncontainer,

a step for processing the substrate or substrates by supplying reactiongas into a reaction container through a nozzle which is attached to saidreaction container such that the nozzle penetrates a wall of thereaction container and in which a flow-path cross-sectional area of aportion of the nozzle opposed to at least a heater is greater than aflow-path cross-sectional area of the attaching portion, and

a step for transferring the processed substrate or substrates out fromthe reaction container.

BRIEF DESCRIPTION OF THE FIGURES IN THE DRAWINGS

FIG. 1 is a schematic longitudinal sectional view for explaining avertical CVD apparatus according to one example of the presentinvention.

FIG. 2 is a transversal sectional view for explaining the vertical CVDapparatus according to the one example of the present invention.

FIG. 3 is a partially enlarged longitudinal sectional view of FIG. 1.

FIG. 4A is a sectional view taken along a line A-A in FIG. 3.

FIG. 4B is a sectional view taken along a line B-B in FIG. 3.

FIG. 5 shows variation in thicknesses of films formed on wafers whenbatch processing is carried out in the substrate processing apparatusaccording to the one example of the present invention.

FIG. 6 is a schematic partial vertical sectional view for explaining astate in which reaction product adheres to a gas introduction nozzle.

FIG. 7 is a schematic partial vertical sectional view for explaining amodification of the gas introduction nozzle.

FIG. 8A is a sectional view taken along a line A-A in FIG. 3 forexplaining a modification of the gas introduction nozzle.

FIG. 8B is a sectional view taken along a line B-B in FIG. 3 forexplaining a modification of the gas introduction nozzle.

FIG. 9A is a sectional view taken along a line A-A in FIG. 3 forexplaining a modification of the gas introduction nozzle.

FIG. 9B is a sectional view taken along a line B-B in FIG. 3 forexplaining a modification of the gas introduction nozzle.

FIG. 10A is a sectional view taken along a line A-A in FIG. 3 forexplaining a modification of the gas introduction nozzle.

FIG. 10B is a sectional view taken along a line B-B in FIG. 3 forexplaining a modification of the gas introduction nozzle.

FIG. 11A is a sectional view taken along a line A-A in FIG. 3 forexplaining a modification of the gas introduction nozzle.

FIG. 11B is a sectional view taken along a line B-B in FIG. 3 forexplaining a modification of the gas introduction nozzle.

FIG. 12A is a sectional view taken along a line A-A in FIG. 3 forexplaining a modification of the gas introduction nozzle.

FIG. 12B is a sectional view taken along a line B-B in FIG. 3 forexplaining a modification of the gas introduction nozzle.

FIG. 13 is a schematic partial longitudinal sectional view forexplaining a conventional vertical CVD apparatus.

PREFERABLE MODE FOR CARRYING OUT THE INVENTION

A preferred embodiment of the present invention will be explained withreference to the drawings below.

Usually, when a polycrystalline silicon film is to be formed, SiH₄ issupplied as reaction gas from a reaction gas supply nozzle. An inside ofa furnace is heated to 610° C., the pressure in the furnace ismaintained at 26.6 Pa and the film is formed.

A flat polycrystalline silicon film is formed for a back seal of asilicon wafer in some cases. In this case, the processing temperature ishigher by 30° C. to 50° C. as compared with normal processing, and thisfilm is formed thicker than the polycrystalline silicon film.

This preferable embodiment of the invention is suitably used for formingsuch polycrystalline silicon film and flat polycrystalline silicon filmand among them, this embodiment is suitably used for forming especiallythe flat polycrystalline silicon film.

FIG. 1 schematically shows a batch type vertical CVD apparatus which isone of substrate processing apparatuses, especially a CVD apparatuswhich forms a flat polycrystalline silicon film, especially a reactionfurnace 1. FIG. 2 is a schematic transverse sectional view forexplaining especially the outline of the reaction furnace 1.

Here, the term “flat” means that the temperature gradient in the furnaceis set flat (substantially zero). Therefore, flat polycrystallinesilicon films are polycrystalline silicon films formed on a plurality ofsubstrates disposed in a furnace in which the temperature gradient isset flat. When the flat polycrystalline silicon film is to be formed,film-forming gas is uniformly supplied to the entire region in thefurnace in which a plurality of substrates are disposed and thus, afilm-forming gas nozzle called a long nozzle is used. Here, the term“long nozzle” means a film-forming gas nozzle capable of supplyingfilm-forming gas not from outside of a region in the furnace where aplurality of substrates are disposed but from inside of the region inthe furnace where the substrates are disposed. In the reaction furnaceof the vertical CVD apparatus, since this long nozzle is usuallyinserted from a lower portion of the furnace and is extended toward anupper portion of the furnace, the long nozzle is longer than a normalnozzle which is inserted from the lower portion within the furnace andterminated therein. To form the flat polycrystalline silicon film, aplurality of, e.g., four quartz long nozzles which extend along a regionin the furnace where the plurality of substrates are disposed and whichhave different lengths are used.

With reference to FIGS. 1 and 2, an upper portion of an evacuationair-tight chamber (not shown) such as a load lock chamber is air-tightlyprovided with a stainless steel furnace opening flange 2 which forms afurnace opening. An inner tube 3 is concentrically supported at adesired position of an inner surface of the furnace opening flange 2, anouter tube 4 is provided on an upper end of the furnace opening flange 2concentrically with the inner tube 3. A cylindrical heater 5 is providedconcentrically with the outer tube 4 such as to surround the outer tube4. Heat insulators 44 are provided such as to cover a periphery and anupper portion of the heater 5. The heater 5 is divided into five zones,i.e., U, CU, C, CL and L. When substrates are to be processed, a maincontrol unit 24 controls such that temperatures of the five zones becomethe same (temperature gradient becomes flat in the vertical direction).A lower end of the furnace opening flange 2 is air-tightly closed by aseal cap 13.

The inner tube 3 is of cylindrical shape whose upper and lower ends areopened. The inner tube 3 is made of quartz or silicon carbide which hasheat resistance property and which does not contaminate wafers. Thewafers are heated equally by accumulating heat from the heater 5,thereby equalizing heating effect of wafers. The outer tube 4 is of abottomed cylindrical shape having an opened lower end and a closed upperend. Like the inner tube 3, the outer tube 4 is made of quartz orsilicon carbide.

A boat 26 is provided in the inner tube 3. A plurality of wafers 30 areloaded on the boat 26 in their horizontal postures. Predetermined gapsare provided between the wafers 30. The boat 26 is mounted on aboat-receiving stage 15 mounted on the seal cap 13. The seal cap 13 onwhich the boat 26 is mounted moves upward, and the lower end of thefurnace opening flange 2 is air-tightly closed. In this state, thewafers 30 loaded on the boat 26 are located at predetermined positions.A plurality of heat insulative plates 41 are placed on a lower portionof the boat 26, 5 to 10 dummy wafers 312 are placed thereon, one monitorwafer 325 is placed thereon, 25 product wafers 304 are placed thereon,one monitor wafer 324 is placed thereon, 25 product wafers 303 areplaced thereon, one monitor wafer 323 is placed thereon, 25 productwafers 302 are placed thereon, one monitor wafer 322 is placed thereon,25 product wafers 301 are placed thereon, one monitor wafer 321 isplaced thereon, and 5 to 10 dummy wafers 311 are placed thereon.

The inner tube 3 and the outer tube 4 constitute a reaction tube. Thefurnace opening flange 2, the inner tube 3, the outer tube 4, the heater5 and the like constitute a vertical furnace. A processing chamber 16 isdefined in the inner tube 3. A cylindrical gas discharge passage 11 isdefined between the inner tube 3 and the outer tube 4. The reactiontubes 3 and 4, the furnace opening flange 2, the seal cap 13 and thelike constitute the reaction container.

A plurality of (four in the drawing) gas introducing nozzles 6, 7, 8 and9 air-tightly penetrate a wall of the furnace opening flange 2 from thehorizontal direction, and extend upward along an inner surface of theinner tube 3, preferably in parallel to an axis of the inner tube 3. Thegas introducing nozzles 6, 7, 8 and 9 are made of quartz, and upper endsof the gas introducing nozzles 6, 7, 8 and 9 are opened as gas ejectionports 63, 73, 83 and 93, respectively. Reaction gas is introduced intothe inner tube 3 through the gas introducing nozzles 6, 7, 8 and 9. Thegas introducing nozzles 6, 7, 8 and 9 penetrate the wall of the furnaceopening flange 2 at the same height in the horizontal direction butlengths of the gas introducing nozzles 6, 7, 8 and 9 are different fromone another. The gas introducing nozzles 6, 7, 8 and 9 respectivelycomprise tube shaft intersecting portions 61, 71, 81 and 91 whichintersect with an axis of the reaction tube, and a tube shaft parallelportions 62, 72, 82 and 92 provided along a tube inner surface inparallel to the axis of the reaction tube. Lengths of the tube shaftparallel portions 62, 72, 82 and 92 are different from one another instages. As a result, heights of upper end positions (gas ejection ports63, 73, 83 and 93) of the gas introducing nozzles 6, 7, 8 and 9 aredifferent from one another in stages.

The reason why the heights of the gas ejection ports 63, 73, 83 and 93of the upper ends of the gas introducing nozzles 6, 7, 8 and 9 is thatin order to secure the uniformity of film thicknesses of the pluralityof wafers 30 while setting the temperature gradient in a direction alongthe tube axis in the reaction furnace 1 to zero, it is necessary todivide a region where the plurality of wafers 30 are disposed into fourzones (product wafers 301, 302, 303 and 304), to allow the plurality ofgas introducing nozzles 6, 7, 8 and 9 to extend into the reactionfurnace 1 such as to correspond to the divided zones respectively, andto supply the reaction gas therefrom.

The gas ejection ports 63, 73, 83 and 93 of the upper ends of the gasintroducing nozzles 6, 7, 8 and 9 are disposed at equal distances fromone another. The gas ejection ports 63, 73, 83 and 93 are located in thevicinity of central portions of arrangement regions of product wafers301, 302, 303 and 304 on which 25 wafers are stacked, respectively.Since the gas ejection ports 63, 73, 83 and 93 of the upper ends of thegas introducing nozzles 6, 7, 8 and 9 are positioned such as torespectively correspond to the product wafers 301, 302, 303 and 304 ofthe four zones in the processing chamber 16, reaction gas is equallysupplied to the plurality of wafers 30.

Reaction gas is consumed by forming films, but since the gas ejectionports 63, 73, 83 and 93 of the upper ends of the gas introducing nozzles6, 7, 8 and 9 are opened upward in stages, reaction gas is introduced insuccession to compensate the consumed reaction gas. The reaction gas isintroduced in equal concentrations from the lower portion to the upperportion of the processing chamber 16 and as a result, film thicknessesof the wafers 30 are equalized.

As shown in FIG. 2, the gas introducing nozzles 6, 7, 8 and 9 aredisposed on the same circumference at equal distances from one anotheralong the inner surface of the inner tube 3. To facilitate theunderstanding of explanation, the inner tube 3 is disposed in the radialdirection in FIG. 1. A gas introduction nozzle 10 is a straight nozzlewhich intersects with the tube axis. The gas introduction nozzle 10 ismade of quartz like the gas introducing nozzles 6, 7, 8 and 9.

As shown in FIGS. 3, 4A and 4B, the tube shaft intersecting portions 61,71, 81 and 91 of the gas introducing nozzles 6, 7, 8 and 9 have smalldiameters (small flow-path cross sections). Portions of the tube shaftparallel portions 62, 72, 82 and 92 which are opposed at least to theheater 5 have large diameters (large flow-path cross sections). Aflow-path cross-sectional area of the large-diameter portion ispreferably at least two times or more of the flow-path cross-sectionalarea of the small-diameter portion.

Concerning a method for obtaining the large flow-path cross section,inner diameters of the tube shaft parallel portions 62, 72, 82 and 92are increased with respect to the tube shaft intersecting portions 61,71, 81 and 91. If the diameters of the tube shaft intersecting portions61, 71, 81 and 91 are reduced to small values (in this embodiment, ¼inches, the same as the conventional outer diameter), this method can becarried out without largely modifying the existing substrate processingapparatus. As shown in FIGS. 4A and 4B, the cross-sectional shapes ofthe tube shaft parallel portions 62, 72, 82 and 92 are formed into along circle or ellipse (elliptic shape) having long shaft in thecircumferential direction. In this case, outer diameters of thereof inthe directions of the short axes are set to the same sizes as those ofthe tube shaft intersecting portions 61, 71, 81 and 91, or determined sothat the tube shaft parallel portions 62, 72, 82 and 92 do not interferewith the boat 26 and the wafer 30 while taking into consideration theinner tube 3 and the boat 26, as well as the gaps between the wafers 30held by the boat 26. In this embodiment, the cross sections of the tubeshaft intersecting portions 61, 71, 81 and 91 are circular having outerdiameters of 5 to 7 mm and inner diameters of 3 to 5 mm. Outer diameters“b” of the tube shaft parallel portions 62, 72, 82 and 92 in the shortaxis direction are 7 to 9 mm, and inner diameters “a” are 5 to 7 mm.Outer diameters “d”of the tube shaft parallel portions 62, 72, 82 and 92in the long axis direction are 10 to 12 mm, and inner diameters “c” are8 to 10 mm.

In this embodiment, the inner diameters of the tube shaft parallelportions 62, 72, 82 and 92 are increased with certain inclination from aportion 51 at which the inner diameters start increasing, and the innerdiameters become constant from a portion 52. This portion 52 is locatedlower than a lower end 53 of the heater 5. The portion 51 at which theinner diameters start increasing is located lower than the heater 5, theouter tube 4 and the heat insulative plates 41, and is higher than lowerends of the boat-receiving stage 15 and the inner tube 3, and is locatedwithin a region opposed to the furnace opening flange 2.

As shown in FIG. 7, the portion 52 at which the inner diameters finishincreasing may be at substantially the same height as the lower end 53of the heater 5 (see (a)), the portion 51 at which the inner diametersstart increasing may be at substantially the same height as the lowerend 53 of the heater 5 (see (b)), and a portion at which the innerdiameters are increasing may be at substantially the same height as thelower end 53 of the heater 5 (see (c)). The inner diameters of the tubeshaft parallel portions 62, 72, 82 and 92 may not be increased with thecertain inclination from the portion 51 at which the inner diametersstart increasing, but the inner diameters may be increased suddenly atthe portion 54. In this case, the portion 54 may be lower than the lowerend 53 of the heater 5 (see (d)), or may be substantially at the sameheight as the lower end 53 of the heater 5 (see (e)). The upper ends ofthe tube shaft parallel portions 62, 72, 82 and 92 may not be providedwith the gas ejection ports 63, 73, 83 and 93. Alternatively, porousnozzles (see (f)) provided a plurality of gas ejection ports 48 on sidesurfaces of the tube shaft parallel portions 62, 72, 82 and 92 may beused. In this case, positions of the portions 51 and 52 are the same asthose of the gas introducing nozzles 6, 7, 8 and 9.

Referring back to FIG. 3, the tube shaft parallel portions 62, 72, 82and 92 and the tube shaft intersecting portions 61, 71, 81 and 91 may beconnected to each other as separate parts or they may be integrallyformed together.

Cushion members 46 are respectively mounted on lower portions of thetube shaft intersecting portions 61, 71, 81 and 91. The cushion members46 are in contact with a metal ring nozzle support member 45 which ismounted such as to project inward from a wall of the furnace openingflange 2.

The furnace opening flange 2 is provided with an exhaust tube 12 whichis in communication with a lower end of the gas discharge passage 11.Reaction gas introduced from the gas introducing nozzles 6, 7, 8, 9 and10 flows upward in the inner tube 3, the reaction gas is turned back atthe upper end of the inner tube 3, and flows downward in the gasdischarge passage 11, and is discharged out from the exhaust tube 12.

Referring back to FIG. 1, an opening (furnace opening) of the lower endof the furnace opening flange 2 is air-tightly closed with the seal cap13. The seal cap 13 is provided with a boat-rotating apparatus 14. Theboat 26 stands on the boat-receiving stage 15 which is rotated by theboat-rotating apparatus 14. The seal cap 13 is supported by a boatelevator 17 such that the seal cap 13 can move vertically.

The gas introducing nozzles 6, 7, 8, 9 and 10 are connected to areaction gas supply source 42 which supplies reaction gas such as SiH₄or the like, or are connected to a purge gas supply source 43 whichsupplies inert gas such as nitrogen gas respectively through mass flowcontrollers 18, 19, 20, 21 and 22 as flow rate controllers.

The main control unit 24 control the heating operation of the heater 5,the vertical movement of the boat elevator 17, rotation of theboat-rotating apparatus 14, and flow rates of the mass flow controllers18, 19, 20, 21 and 22. A temperature detection signal from one or moretemperature detectors 25 which detect the temperature in the furnace isinput to the main control unit 24, and the heater 5 is controlled suchthat the heater 5 equally heats inside of the furnace.

The operation will be explained below.

The boat 26 is lowered by the boat elevator 17, and wafers 27 are loadedon the lowered boat 26 by a substrate loader (not shown). In a state inwhich a predetermined number of wafers 27 are loaded, the boat elevator17 moves the seal cap 13 upward to bring the boat 26 into the processingchamber 16. The processing chamber 16 is air-tightly closed with theseal cap 13, the processing chamber 16 is decompressed to a processingpressure through the exhaust tube 12, and the processing chamber 16 isheated to the processing temperature by the heater 5. The boat 26 isrotated around the vertical axis by the boat-rotating apparatus 14.

The mass flow controllers 18, 19, 20, 21 and 22 control the flow rate ofthe reaction gas (SiH₄), and the reaction gas is introduced into theprocessing chamber 16 through the gas introducing nozzles 6, 7, 8, 9 and10. The reaction gas (SiH₄) may be 100% SiH₄ and introduced alone, orSiH₄ may be diluted with N₂ and introduced.

During the process in which reaction gas flows upward in the processingchamber 16, reaction product is deposited on the wafers 27 bythermochemical reaction and films are formed. Since the boat 26 isrotated, the reaction gas is prevented from unevenly flowing withrespect to the wafers 27.

Reaction gas is consumed by forming films, but since the upper endpositions (gas introducing positions) of the gas introducing nozzles 6,7, 8 and 9 are opened upward in stages, reaction gas is introduced insuccession to compensate the consumed reaction gas. The reaction gas isintroduced in equal concentrations from the lower portion to the upperportion of the processing chamber 16. Therefore, film thicknesses of thewafers are equalized.

The mass flow controllers 18, 19, 20, 21 and 22 control the amount ofgas to be introduced from the gas introducing nozzles 6, 7, 8, 9 and 10such that the concentration of reaction gas becomes constant.

Reaction gas is heated by the heater 5 during the process in which thereaction gas passes through the tube shaft intersecting portions 61, 71,81 and 91 and flows upward in the tube shaft parallel portions 62, 72,82 and 92. Therefore, while the reaction gas passes through the tubeshaft parallel portions 62, 72, 82 and 92, reaction product adheres toinner surfaces of the tube shaft parallel portions 62, 72, 82 and 92 insome cases. As described above, portions of the tube shaft parallelportions 62, 72, 82 and 92 which are opposed at least to the heater 5are large in diameters. Thus, even if reaction product 47 adheres asshown in FIG. 6, the gas introducing nozzles 6, 7, 8 and 9 are notclogged.

Further, since the temperatures in the tube shaft intersecting portions61, 71, 81 and 91 are low and reaction does not proceed and thus, thediameters of the tube shaft intersecting portions 61, 71, 81 and 91 maybe left thin. As shown in FIG. 3, joint portion areas between the tubeshaft intersecting portions 61, 71, 81 and 91 and the tube shaftparallel portions 62, 72, 82 and 92, or portions of the tube shaftparallel portions 62, 72, 82 and 92 which are not opposed to the heater5 and which rise from the tube shaft intersecting portions 61, 71, 81and 91 are small in diameters because temperatures thereof are less than300 to 400° C. and reaction does not proceed.

Even the portions of the tube shaft parallel portions 62, 72, 82 and 92opposed to the heater 5, temperatures in lower portions of these portionare less than 300 to 400° C. and these portions are not heated so muchand thus, these lower portion may be left small in diameters. Portionsof the tube shaft parallel portions 62, 72, 82 and 92 which areincreased on flow-path cross sections and which are opposed to theheater 5 maybe defined as regions where the wafers 30 are accommodated.

Therefore, even when films are repeatedly formed, clogging of the nozzlecan be suppressed, the supply amount of reaction gas from the gasintroducing nozzles 6, 7, 8 and 9 does not become insufficient, andsubstrates can be processed with excellent quality. Effect can beexpected in forming processing of polycrystalline silicon thick film,preferably flat polycrystalline silicon thick film. The presentinvention can also be applied to forming processing of SiGe films whichis carried out using silane-based gas such as SiH₄ and germane-based gassuch as GeH₄.

A portion of the nozzle where it is required to increase a flow-pathcross-sectional area is a portion whose temperature becomes such adegree that film-forming reaction is generated (portion where itstemperature becomes 300 to 400° C. or higher in the case of SiH₄), or aportion whose temperature becomes such a degree that reaction gas isdissolved (portion where its temperature becomes 300 to 400° C. orhigher in the case of SiH₄).

A portion of the nozzle where it is not required to increase theflow-path cross-sectional area is a nozzle-attaching portion, a nozzlehorizontal portion, a nozzle bent portion, a portion which is notopposed to the heater, and a portion whose temperature becomes such adegree that film-forming reaction is not generated (portion where itstemperature becomes less than 300 to 400° C. in the case of SiH₄), or aportion whose temperature becomes such a degree that reaction gas is notdissolved (portion where its temperature becomes less than 300 to 400°C. in the case of SiH₄).

FIG. 5 shows variation in thicknesses of films formed on wafers whenbatch processing is carried out in a substrate processing apparatus ofthe present invention.

Preferable processing conditions are that film-forming temperature,i.e., temperature in a region of at least the processing chamber 16where the wafers 30 are accommodated is 650 to 670° C., film-formingpressure is 10 to 30 Pa, thickness of formed film is 5,000 to 10,000 Å,and reaction gas flow rate (SiH₄, total flow rate: 0.2 to 1 SLM).

FIG. 5 shows a case in which the batch processing is repeated ten timesunder the above processing conditions. There is a tendency that theaverage film thickness (average film thickness value of wafers subjectedto the same batch processing) is gradually increased with each batchprocessing, but the uniformity of film thicknesses with each batchprocessing is ±0.38% and falls within a range where product quality isnot harmed, clogging of the nozzle can be suppressed, and the supplyamount of reaction gas does not become insufficient. Conventionally, thenozzle is clogged after batch processing is repeated three to fourtimes, but according to this embodiment, it has been confirmed that thebatch processing can be carried out ten or more times.

If the mass flow controllers 18, 19, 20, 21 and 22 are controlled bycollecting data concerning uniformity of film thicknesses with everybatch processing and by grasping the tendency, and if the flow rate iscontrolled with each batch processing, the uniformity of filmthicknesses is enhanced.

Although the film-forming temperature is 650 to 670° C. in the aboveembodiment, the film-forming temperature may be 620° C. or higher. Forexample, the film-forming temperature may be 620 to 680° C. The tubeshaft parallel portions 62, 72, 82 and 92 can be produced by crushingtubes of ⅜ inches for example. Cross-sectional shapes of the tube shaftparallel portions are not limited to circular, long circular or ellipticshape. The cross-sectional shape may be arc long circular shape or arectangular having long sides in the circumferential direction. Inshort, the cross-sectional shape is not limited only if the flow-pathcross section can be enlarged. Preferable examples of thecross-sectional shape are squashy circular shape, substantially ellipticshape, crushed circular shape (elliptic shape, egg-like shape, roundedrectangular shape, shape in which ends of opposed semi-circles areconnected with each other through straight lines), substrate ellipticshape in which short axis is oriented toward a central portion of asubstrate, a substantially elliptic shape having short axis in adirection of a straight line which connects a center of a substrate anda center of a nozzle, a substantially elliptic shape having long axis ina direction substantially perpendicular to a straight line whichconnects the center of the substrate and the center of the nozzle, ashape in which a width in a direction of a straight line which connectsthe center of the substrate and the center of the nozzle is smaller thana width in a direction which is substantially perpendicular to theformer width, a rectangular shape having long sides in a directionsubstantially perpendicular to the straight line which connects thecenter of the substrate and the center of the nozzle, and a rhombusshape having long sides in a direction substantially perpendicular tothe straight line which connects the center of the substrate and thecenter of the nozzle. FIGS. 8A to 12B show such modifications.

The present invention can also be carried out even if the reactionfurnace is a lateral reaction furnace.

As explained above, in this embodiment, the flow-path cross-sectionalarea of a portion of the nozzle that is opposed at least to the heateris set greater than the flow-path cross-sectional area of the attachingportion of the nozzle on the reaction container. Therefore, it ispossible to suppress the clogging of the nozzle, and to increase thenumber of processing which can be carried out until maintenance isrequired. With this, a frequency of the maintenance can be reduced(maintenance cycle can be increased), and downtime of the apparatus canbe reduced.

The flow-path cross-sectional area of the attaching portion of thenozzle on the reaction container is not increased and the same shape asthat of the conventional technique (¼ inch diameter) can be employed andthus, a furnace opening flange having the same shape as that of theconventional technique (corresponding to nozzle of ¼ inch diameter) canbe used as it is, and it is unnecessary to newly design the furnaceopening flange. When the flow-path cross-sectional area of the entirenozzle is increased, it is necessary to newly design (change the designof) the furnace opening flange such in accordance with the changednozzle shape.

Since the cross-sectional shape of the portion of the nozzle that isopposed to the heater is the squashy circular shape (elliptic shape),clearance between the wafer and the inner tube can be reduced. Withthis, the gas concentration over the entire surface of a substrate canbe equalized, and uniformity of film thickness over the entire surfaceof the substrate and uniformity of film quality over the entire surfaceof the substrate can be enhanced. Further, the volume of the reactiontube can be reduced, and an amount of gas to be used can be saved.Further, the apparatus can be reduced in size.

The entire disclosures of Japanese Patent Application No. 2003-206526filed on Aug. 7, 2003 and Japanese Patent Application No. 2004-096063filed on Mar. 29, 2004 each including specification, claims, drawingsand abstract are incorporated herein by reference in those entirety.

Although various exemplary embodiments have been shown and described,the invention is not limited to the embodiments shown. Therefore, thescope of the invention is intended to be limited solely by the scope ofthe claims that follow.

INDUSTRIAL APPLICABILITY

As explained above, according to the embodiment of the presentinvention, in a substrate processing apparatus having a reaction tubewhich processes a plurality of substrates, a heater which heats thesubstrates, and at least one gas introduction nozzle through which gasis supplied into the reaction tube, a flow-path cross section of aportion of the gas introduction nozzle that is opposed at least theheater is greater than flow-path cross section of other portion.Therefore, it is possible to exhibit excellent effects that when filmsare to be formed, clogging of the gas introduction nozzle can besuppressed, maintenance operation is reduced, maintenance cycle can beshortened, and throughput can be enhanced.

As a result, the present invention can suitably be utilized especiallyfor a vertical CVD apparatus which produces a semiconductor device on asilicon wafer, and for a producing method of a semiconductor devicewhich uses this CVD apparatus.

1. A substrate processing apparatus, comprising: a reaction container toprocess a plurality of substrates; a heater to heat said plurality ofsubstrates; and a plurality of nozzles having different lengths throughwhich reaction gas is to be supplied into said reaction container,wherein each of said plurality of nozzles includes a horizontal portionextending in a horizontal direction and a vertical portion rising in avertical direction, said horizontal portion is attached to a sidewall ofsaid reaction container with said horizontal portion penetrating thesidewall of said reaction container, said vertical portion is disposedin said reaction container apart from an inner wall of said reactioncontainer such that a portion of the vertical portion is opposed to saidheater, a flow-path cross-sectional area of the portion of said verticalportion that is opposed to at least said heater is greater than aflow-path cross-sectional area of said horizontal portion, and aflow-path cross-sectional shape of the portion of said vertical portionthat is opposed to at least said heater is formed into a substantiallyelliptic shape with a short axis thereof oriented toward a centralportion of the substrate.
 2. A substrate processing apparatus as recitedin claim 1, wherein said cross-sectional shape of the horizontal portionof said nozzle is formed into a circular shape.
 3. A substrateprocessing apparatus as recited in claim 1, wherein said heater isdivided into a plurality of heater zones, and when said substrate isprocessed, temperatures in the reaction container corresponding to therespective heater zones are maintained at the same temperatures.
 4. Aproducing method of a semiconductor device, comprising: transferring aplurality of substrates into a reaction container; processing theplurality of substrates by supplying reaction gas into the reactioncontainer heated by a heater through a plurality of nozzles havingdifferent lengths, each of said plurality of nozzles having a horizontalportion extending in a horizontal direction and a vertical portionrising in a vertical direction, said horizontal portion being attachedto a sidewall of said reaction container such that the horizontalportion penetrates the sidewall of the reaction container, said verticalportion being disposed in said reaction container apart from an innerwall of said reaction container such that a portion of the verticalportion is opposed to said heater disposed to heat the plurality of thesubstrates, a flow-path cross-sectional area of the portion of thevertical portion opposed to at least the heater being greater than aflow-path cross-sectional area of the horizontal portion, a flow-pathcross-sectional shape of the portion of said vertical portion that isopposed to at least said heater being formed into a substantiallyelliptic shape with a short axis thereof oriented toward a centralportion of the substrate; and transferring the processed plurality ofsubstrates out from the reaction container.
 5. A substrate processingapparatus, comprising: a reaction container to process a plurality ofsubstrates; a heater to heat the plurality of substrates; and a firstnozzle and at least one second nozzle to supply reaction gas into thereaction container, wherein the first nozzle is attached to a sidewallof said reaction container with said first nozzle penetrating thesidewall of said reaction container and is disposed in the reactioncontainer such that the first nozzle is not opposed to the heater, theat least one second nozzle comprises a plurality of nozzles havingdifferent lengths, each of the plurality of nozzles includes ahorizontal portion extending in a horizontal direction and a verticalportion rising in a vertical direction, said horizontal portion isattached to a sidewall of said reaction container with said horizontalportion penetrating the sidewall of said reaction container, saidvertical portion is disposed in the reaction container apart from aninner wall of said reaction container such that a portion of thevertical portion is opposed to the heater, a flow-path cross-sectionalarea of the portion of the vertical portion that is opposed to at leastthe heater is greater than a flow-path cross-sectional area of thehorizontal portion and a flow-path cross-sectional area of the firstnozzle, and a flow-path cross-sectional shape of the portion of saidvertical portion that is opposed to at least said heater is formed intoa substantially elliptic shape with a short axis thereof oriented towarda central portion of the substrate.
 6. A producing method of asemiconductor device, comprising: loading at least one substrate into areaction container; processing the at least one substrate by supplyingreaction gas into the reaction container heated by a heater through afirst nozzle, and a second nozzle, the first nozzle being attached to asidewall of said reaction container with said first nozzle penetratingthe sidewall of said reaction container and being disposed in thereaction container such that the first nozzle is not opposed to theheater, the second nozzle comprising a plurality of nozzles havingdifferent lengths, each of the plurality of nozzles including ahorizontal portion extending in a horizontal direction and a verticalportion rising in a vertical direction, said horizontal portion beingattached to a sidewall of said reaction container with said horizontalportion penetrating the sidewall of said reaction container, saidvertical portion being disposed in the reaction container apart from aninner wall of said reaction container such that a portion of thevertical portion is opposed to the heater, a flow-path cross-sectionalarea of the portion of the vertical portion that is opposed to at leastthe heater being greater than a flow-path cross-sectional area of thehorizontal portion and a flow-path cross-sectional area of the firstnozzle, a flow-path cross-sectional shape of the portion of saidvertical portion that is opposed to at least said heater being formedinto a substantially elliptic shape with a short axis thereof orientedtoward a central portion of the substrate; and unloading the at leastone substrate from the reaction container after the processing.